District



No. 606,725. 'PatentadJuly 5, T898.

T. H. MACDONALD.

MANUFACTURE OF GBAPH'OPHONE TABLETS.

- (Application filed Nov. 27, 1896.)

(No Model.)

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UNITEDCSTATES PATE T OFFICE.

THOMAS H. MACDONALD, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR To THE AMERICAN GRAPHOPHONE'OOMPANY, OF WASHINGTON, DISTRICT OF COLUMBIA.

MANUFACTURE OF-GRAPHOPHONE-TABL ETS.

SPECIFICATION forming part of Letters Patent No. 606,725, dated July 5, 1898.

Application filed November 27, 1896. Serial No. 613,615. (No specimens.)

To all whom it may concern:

Be it known that I, THOMAS H. MACDONALD, of Bridgeport, Connecticut, have invented new and useful Improvements in the Manufacture of Graphophone-Tablets, which improvements are fully set forth in the following specification.

This invention relates to the manufacture of tablets or blanks adapted to receive engraved records of sounds, and moreparticularly to the composition of matter of which the tablet is composed,

The recording material in order to answer well the requirements of the engraving method of recording sounds should beperfectly amorphous, slightly cohesive, and ca-' pable of being removed cleanly and smoothly in chips or shavings under the actionof the recording-stylus when actuated by the feeble force of sound-waves. The material, moreover, should be sufficiently hard to withstand ordinary handling, to retain perfectly its form, and to resist the effect of ordinary changes of temperature. It shouldalso be a stable compound or material in order that records made in it may be preserved for indefinite lengths of time.

As pointed out in Letters Patent No. 341,214, granted May 4, 1886, to O. A. Bell and S. Tainter, the properties above indicated reside in a greater orless degree in wax and waxlike substances-such as beeswax, paraffin, stearin, (ho-though by special preparation of these and similar substances their fitness for the purpose in View has been increased.

, It has been heretofore proposed to use as a sound-recording material an insoluble soap made by saponification of any fatty acid by means of an earthy alkali, such as lime. It has also been proposed to employ a metal, such as lead, combined with stearic or oleic acid, and particularly a mixture of oleate and stearate of lead; but tablets made of insolu ble lime-soap or of stearates or oleates of lead have never yielded commerciallysuccessful results. Several practical difficulties have been encountered in endeavoring to make tablets composed wholly or in part of soap. The chief difficulty has been that the surfaces of tates of lead. Another difficulty that arises is the formation of crystalline or crystallizable compounds in-the operation of making soap. The object of introducing a metal (or metallic salt) is to prevent all tendency to crystallization, it being of the first importance to secure a composition which shall be and under all conditions remain perfectly amorphous and presenting equal resistance to cutting in every direction. All ordinary commercial soaps have this tendency to crystallization in some degree, it not being possible to introduce sufficient sodium or soda salt to prevent all crystallization.

The accompanying drawing illustrates a common form of tablet for use in receiving engraved records of sounds.

In carrying out my invention, whereby all the conditions herein pointed out as essential are secured, I take stearic acid as nearly pure as can be obtained and convert it into soda soap in the manner hereinafter explained. The composition, however, differs from ordinary soap in that it contains no oleates, I having found that the presence of even a small quantity of oleate or oleic acid is detrimental. It is also important that the tallow or other source from which the stearic acid is obtained be completely deglycerinized. Except under these conditions the result will be'unsatis factory.

In converting the stearic acid into soap I produce only a partial saponificatiom-that is to say, instead of using the chemical equivalent in caustic alkali of the fat acid I use about forty per cent. of that quantity of alkalithus producing what may be called a soap of about two-fifths saponiiication. This is the proportion which gives the best results, but is of course variable within limits. The controlling consideration is that the greater the quantity of alkali the higher will be the melting-point of the resulting soap,anda complete saponilication will produce a soap which requires to melt at a temperature which will char it. As the material is to be molded into cylindrical or other forms, it must be capable of melting, at a moderate temperature, say between 250 and 330 Fahrenheit. On the other hand, if the saponification be not carried far enough the material will be too soft and will run at a lower temperature than is desired. In this soap I have incorporated aluminium, which I have found to be the metal best suited in all respects for the purpose. This may be used in the form of aluminic hydrate or in the metallic state, powdered, or in small ingots. The method of introducing the metal is, moreover, important, owing to the tendency of sodium and aluminium when combined to form crystallizable compounds. Preferably the metal is first added to the soda-lye, forming with a portion thereof aluminate of soda, (sodium-ortho-aluminate,) which readily unites with the stearic acid subsequently added. The quantity of aluminium employed is relatively Very small. In order that the invention may be fully understood, I will give two formulas which have yielded the best results obtained.

Formula A: Stearic acid, free from oleic acid and glycerin, four hundred and eight pounds; aluminic hydrate, seven pounds; caustic-soda lye, eighty-five pounds. To this is added, for the purpose of tempering, para llin, ozokerite, or similar material, seventy-two pounds. The caustic soda is incorporated in water until a lye of 37.5 Baum is obtained, and this is heated to its boilingpoint, about 2l2 Fahrenheit. The aluminic hydrate is added and is quickly taken up by thelye. The stearic acid is melted and raised to about the same temperature and the compound of lye and aluminium added slowly thereto. It will unite readily therewith. It is preferred to employ about the temperature indicated, as thereby the formation of the composition proceeds gradually and without violent ebullition. The temperature may subsequently be raised to about 300 Fahrenheit and continued at that heat until the water is all expelled. The composition is now completed except for the addition of a material such as paraflin, ozokerite, or ce'resin to bring it to the desired degree of hardness.

Formula B: Stea-ric acid, three hundred pounds; powdered aluminium, 1.5 pounds; caustic-soda lye, 37.5 Baume, nine pounds; sal-soda dissolved in twelve gallons of water, sixty pounds; ceresin, sixty pounds. The sal-soda lye and caustic-soda lye may be united before the aluminium is added, or the latter may be added to the caustic soda and the two liquids then united. Instead of powdered aluminium I may use ordinary ingotaluminium with results nearly if not equally as good. After the material is molded to the desired form it should be quickly cooled to ordinary temperatures.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The process of making a sound-recordin g material,by dissolving aluminium in sodalye, and adding the solution to stearic acid, substantially as described.

2. The process of making a sound-record ing material by melting stearic acid, free from glycerin and oleatcs, adding thereto soda-lye and aluminium, and heating the mass, substantially as described.

3. In the process of making a sound-recording material, the improvement consisting in adding to stearic acid soda-lye with which a metal such as aluminium has been united in such quantity as to produce partial saponification, and heating the mixture, substantially as described.

4. The process of making a sound-recording material by treating stearic acid with sodalye in quantity suflicient to produce about a forty-per-eent. saponification, the lye containing a metal and heating the mixture, substantially as described.

5. The process of making a sound-recording material by forming a soda-lye, heating to about its boiling-point, adding a small quantity of aluminium thereto, heating pure stearic acid to about the same temperature, adding the compound of lye and aluminium and continuing the heating until the moisture is expelled, substantially as described.

6. The process of making a graphophonetablet by forming a soda-lye, heating to about its boiling-point, adding a small quantity of aluminium thereto, heating pure stearic acid to about the same temperature, adding the compound, continuing the heating until the moisture is expelled, molding into the desired shape and then quickly cooling, substantially as described.

7. The process of making a sound-recording material, by partial saponilication of stearic acid with soda-lye having aluminium. united therewith, substantially as described.

8. The process of making a sound-recordin g material, by adding aluminic hydrate to caustic-soda lye, adding the compound to melted stearic acid, and heating the mixture, substantially as described.

9. The process of making a sound-recording material, by adding aluminium to sodalye, adding the same to stearic acid, heating the mixture, and adding a softening material such as paraffin, substantially as described.

10. A composition of matter for a soundrecording tablet formed of pure stoaric acid (free from 01010 acid and glycerin) partly saponified by caustic soda, and having alu- In testimony whereof I have signed this minium incorporated therein, substantially specification in the presence of two subscribas described. ing witnesses;

11. The process of making a sound-record- THOMAS H. MACD NALD. 5 ing material by adding aluminate of soda to Witnesses:

stearic acid and heating the mixture, sub- S. T. CAMERON,

stantially as described. 7 REEVE LEWIS. 

